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Commutative morph optimizations #64122

Merged
merged 4 commits into from
Jan 28, 2022
Merged

Commutative morph optimizations #64122

merged 4 commits into from
Jan 28, 2022

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SingleAccretion
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@SingleAccretion SingleAccretion commented Jan 21, 2022 •
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As promised in #63251, there was some low-hanging fruit in the code. This change picks it:

  1. Make better use of optimization order.
  2. Fold x + 0 for CNS_LNG too.
  3. Drop one unnecessary fgGlobalMorph guard.
  4. Finally, disable the "mulshift" optimization on non-XARCH targets.

Diffs. Win-x64 diffs didn't make it for unclear reasons, here's the locally obtained version: win-x64 diffs.

@dotnet-issue-labeler dotnet-issue-labeler bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Jan 21, 2022
@ghost ghost added the community-contribution Indicates that the PR has been added by a community member label Jan 21, 2022
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As promised in #63251, there was some low-handing fruit in the code. This change picks it up:

  1. Make better use of optimization order.
  2. Fold x + 0 for CNS_LNG too.
  3. Drop one unnecessary fgGlobalMorph guard.
  4. Finally, disable the "mulshift" optimization on non-XARCH targets.

We are expecting some pretty nice diffs form all the above combined.

Author: SingleAccretion
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area-CodeGen-coreclr
Milestone: -

@SingleAccretion SingleAccretion changed the title Commutative morph opt Commutative morph optimizations Jan 21, 2022
@SingleAccretion SingleAccretion marked this pull request as ready for review January 22, 2022 12:48
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@JulieLeeMSFT JulieLeeMSFT added this to the 7.0.0 milestone Jan 25, 2022
@SingleAccretion
Optimize order of morphing
a4a221c 
"fgMorphCommutative" exposes information to the later
transforms that make them more precise.

For example, "MUL(MUL(X, CONST1), CONST2)" is now morphed
properly into a single "mul" instead of one "mul" plus a shift
and lea in case "CONST2" was a viable candidate for "mulshift".

Another example is how "fgMorphCommutative" can end up with an
"ADD(X, 0)" that was only being discarded in lowering.
@SingleAccretion
Fold (x + 0) => 0 for LONGs on 32 bit
c35e310
@SingleAccretion
Enable one opt outside global morph
6a8543e 
No reason not to. Just a few diffs.
@SingleAccretion
Disable mulshift on ARM/64
d3b168b 
No LEAs - no point.
@BruceForstall BruceForstall merged commit d06d9c9 into dotnet:main Jan 28, 2022
@SingleAccretion SingleAccretion deleted the Commutative-Morph-Opt branch January 28, 2022 20:24
@kunalspathak kunalspathak mentioned this pull request Feb 24, 2022
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@BruceForstall BruceForstall BruceForstall approved these changes

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@SingleAccretion SingleAccretion

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